(CNN) -- FoxNews.com alerted the Secret Service on Monday about the apparent hacking of its Twitter feed for political news, after the feed was used to falsely report that President Obama was killed.
Jeff Misenti, Fox News Digital's vice president and general manager, said in a statement that the website has also requested "a detailed investigation from Twitter about how this occurred, and measures to prevent future unauthorized access into FoxNews.com accounts."
Secret Service spokesman George Ogilvie said Monday that his agency "will be investigating the matter and will conduct the appropriate follow up."
The false tweets were taken down from the site after being up for hours.
One of the tweets from @FoxNewsPolitics said Obama was "shot twice at a Ross' restaurant in Iowa while campaigning. RIP Obama, best regards to the Obama family."
"We wish @joebiden the best of luck as our new President of the United States. In such a time of madness, there's light at the end of tunnel," the last in the series of tweets said later.
An article on FoxNews.com confirmed the hack.
"Hackers sent out several malicious and false tweets claiming that President Obama had been assassinated," it said. "Those reports are incorrect, of course, and the president is spending the July 4 holiday with his family.
"The hacking is being investigated, and FoxNews.com regrets any distress the false tweets may have created."
But six tweets related to the fake news remained on the Fox News Politics twitter feed hours after the apology was posted.
Later, Fox News announced the tweets were removed.
One of the false messages said, "It's a sad 4th of July ... The shooter will be found." That message encouraged Twitter users to repost the message on their own Twitter accounts, which would spread the fake news. Several users did just that.
The tweets generated headlines around the world, as well as criticism and mockery on Twitter, with firebrand liberal TV host Keith Olbermann frantically tweeting to many individual Twitter users that Obama is fine. He asked Twitter users not to re-post the messages.
The first of the false tweets about Obama was posted about 2 a.m. ET.
The Twitter messages asserting that Obama had been attacked came after a message that said, "Just regained full access to our Twitter and email. Happy 4th."
A student journalist interviewed someone claiming to be a representative of the hackers shortly before the Obama tweets were posted.
Adam Peck of Stony Brook University's Think magazine reported that the hackers, calling themselves the Script Kiddies, were an offshoot of the hacker group Anonymous.
"Without groups like Anonymous, what is there to prevent corruption?" he quoted the representative as saying.
Peck interviewed the representative via instant message, contacting an account he said they used to send out the tweets and later deleted. He said they had posted several innocuous fake messages before sending the Obama tweets, then deleted them.
He said he could not confirm that the person he interviewed was really one of the hackers but "firmly" believed it, based on the link between fake posts on Twitter and the instant message account.
The instant message address he gave to CNN for the hackers was offline Monday morning.
The @FoxNewsPolitics Twitter account had 34,566 followers Monday morning but by afternoon had more than 37,000.
Twitter spokeswoman Jodi Olsen said the company did not comment on individual accounts, declining to answer questions about whether @FoxNewsPolitics had been hacked or why the account of the alleged hackers was suspended.
Hours later, the San Francisco-based technology company issued a statement saying Fox News has identified that it was first compromised in another way, which in turn allowed for the alleged perpetrators to access the network's Twitter account.
"While Twitter does monitor accounts for brute-force login attempts and similar methods of attack, we're unable to anticipate compromises that take place due to offsite behavior," Twitter spokesman Matt Graves said in its statement.
CNN's Richard Allen Greene contributed to this report.